lib/string.c

   1 /*
   2  *  linux/lib/string.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 /*
   8  * stupid library routines.. The optimized versions should generally be found
   9  * as inline code in <asm-xx/string.h>
  10  *
  11  * These are buggy as well..
  12  *
  13  * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
  14  * -  Added strsep() which will replace strtok() soon (because strsep() is
  15  *    reentrant and should be faster). Use only strsep() in new code, please.
  16  *
  17  * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>,
  18  *                    Matthew Hawkins <matt@mh.dropbear.id.au>
  19  * -  Kissed strtok() goodbye
  20  */
  21
  22 #include <linux/types.h>
  23 #include <linux/string.h>
  24 #include <linux/ctype.h>
  25 #include <linux/module.h>
  26
  27 #ifndef __HAVE_ARCH_STRNICMP
  28 /**
  29  * strnicmp - Case insensitive, length-limited string comparison
  30  * @s1: One string
  31  * @s2: The other string
  32  * @len: the maximum number of characters to compare
  33  */
  34 int strnicmp(const char *s1, const char *s2, size_t len)
  35 {
  36         /* Yes, Virginia, it had better be unsigned */
  37         unsigned char c1, c2;
  38
  39         c1 = 0; c2 = 0;
  40         if (len) {
  41                 do {
  42                         c1 = *s1; c2 = *s2;
  43                         s1++; s2++;
  44                         if (!c1)
  45                                 break;
  46                         if (!c2)
  47                                 break;
  48                         if (c1 == c2)
  49                                 continue;
  50                         c1 = tolower(c1);
  51                         c2 = tolower(c2);
  52                         if (c1 != c2)
  53                                 break;
  54                 } while (--len);
  55         }
  56         return (int)c1 - (int)c2;
  57 }
  58
  59 EXPORT_SYMBOL(strnicmp);
  60 #endif
  61
  62 #ifndef __HAVE_ARCH_STRCPY
  63 /**
  64  * strcpy - Copy a %NUL terminated string
  65  * @dest: Where to copy the string to
  66  * @src: Where to copy the string from
  67  */
  68 #undef strcpy
  69 char * strcpy(char * dest,const char *src)
  70 {
  71         char *tmp = dest;
  72
  73         while ((*dest++ = *src++) != '\0')
  74                 /* nothing */;
  75         return tmp;
  76 }
  77 EXPORT_SYMBOL(strcpy);
  78 #endif
  79
  80 #ifndef __HAVE_ARCH_STRNCPY
  81 /**
  82  * strncpy - Copy a length-limited, %NUL-terminated string
  83  * @dest: Where to copy the string to
  84  * @src: Where to copy the string from
  85  * @count: The maximum number of bytes to copy
  86  *
  87  * The result is not %NUL-terminated if the source exceeds
  88  * @count bytes.
  89  */
  90 char * strncpy(char * dest,const char *src,size_t count)
  91 {
  92         char *tmp = dest;
  93
  94         while (count) {
  95                 if ((*tmp = *src) != 0) src++;
  96                 tmp++;
  97                 count--;
  98         }
  99         return dest;
 100 }
 101 EXPORT_SYMBOL(strncpy);
 102 #endif
 103
 104 #ifndef __HAVE_ARCH_STRLCPY
 105 /**
 106  * strlcpy - Copy a %NUL terminated string into a sized buffer
 107  * @dest: Where to copy the string to
 108  * @src: Where to copy the string from
 109  * @size: size of destination buffer
 110  *
 111  * Compatible with *BSD: the result is always a valid
 112  * NUL-terminated string that fits in the buffer (unless,
 113  * of course, the buffer size is zero). It does not pad
 114  * out the result like strncpy() does.
 115  */
 116 size_t strlcpy(char *dest, const char *src, size_t size)
 117 {
 118         size_t ret = strlen(src);
 119
 120         if (size) {
 121                 size_t len = (ret >= size) ? size-1 : ret;
 122                 memcpy(dest, src, len);
 123                 dest[len] = '\0';
 124         }
 125         return ret;
 126 }
 127 EXPORT_SYMBOL(strlcpy);
 128 #endif
 129
 130 #ifndef __HAVE_ARCH_STRCAT
 131 /**
 132  * strcat - Append one %NUL-terminated string to another
 133  * @dest: The string to be appended to
 134  * @src: The string to append to it
 135  */
 136 #undef strcat
 137 char * strcat(char * dest, const char * src)
 138 {
 139         char *tmp = dest;
 140
 141         while (*dest)
 142                 dest++;
 143         while ((*dest++ = *src++) != '\0')
 144                 ;
 145
 146         return tmp;
 147 }
 148 EXPORT_SYMBOL(strcat);
 149 #endif
 150
 151 #ifndef __HAVE_ARCH_STRNCAT
 152 /**
 153  * strncat - Append a length-limited, %NUL-terminated string to another
 154  * @dest: The string to be appended to
 155  * @src: The string to append to it
 156  * @count: The maximum numbers of bytes to copy
 157  *
 158  * Note that in contrast to strncpy, strncat ensures the result is
 159  * terminated.
 160  */
 161 char * strncat(char *dest, const char *src, size_t count)
 162 {
 163         char *tmp = dest;
 164
 165         if (count) {
 166                 while (*dest)
 167                         dest++;
 168                 while ((*dest++ = *src++) != 0) {
 169                         if (--count == 0) {
 170                                 *dest = '\0';
 171                                 break;
 172                         }
 173                 }
 174         }
 175
 176         return tmp;
 177 }
 178 EXPORT_SYMBOL(strncat);
 179 #endif
 180
 181 #ifndef __HAVE_ARCH_STRLCAT
 182 /**
 183  * strlcat - Append a length-limited, %NUL-terminated string to another
 184  * @dest: The string to be appended to
 185  * @src: The string to append to it
 186  * @count: The size of the destination buffer.
 187  */
 188 size_t strlcat(char *dest, const char *src, size_t count)
 189 {
 190         size_t dsize = strlen(dest);
 191         size_t len = strlen(src);
 192         size_t res = dsize + len;
 193
 194         /* This would be a bug */
 195         BUG_ON(dsize >= count);
 196
 197         dest += dsize;
 198         count -= dsize;
 199         if (len >= count)
 200                 len = count-1;
 201         memcpy(dest, src, len);
 202         dest[len] = 0;
 203         return res;
 204 }
 205 EXPORT_SYMBOL(strlcat);
 206 #endif
 207
 208 #ifndef __HAVE_ARCH_STRCMP
 209 /**
 210  * strcmp - Compare two strings
 211  * @cs: One string
 212  * @ct: Another string
 213  */
 214 #undef strcmp
 215 int strcmp(const char * cs,const char * ct)
 216 {
 217         register signed char __res;
 218
 219         while (1) {
 220                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 221                         break;
 222         }
 223
 224         return __res;
 225 }
 226 EXPORT_SYMBOL(strcmp);
 227 #endif
 228
 229 #ifndef __HAVE_ARCH_STRNCMP
 230 /**
 231  * strncmp - Compare two length-limited strings
 232  * @cs: One string
 233  * @ct: Another string
 234  * @count: The maximum number of bytes to compare
 235  */
 236 int strncmp(const char * cs,const char * ct,size_t count)
 237 {
 238         register signed char __res = 0;
 239
 240         while (count) {
 241                 if ((__res = *cs - *ct++) != 0 || !*cs++)
 242                         break;
 243                 count--;
 244         }
 245
 246         return __res;
 247 }
 248 EXPORT_SYMBOL(strncmp);
 249 #endif
 250
 251 #ifndef __HAVE_ARCH_STRCHR
 252 /**
 253  * strchr - Find the first occurrence of a character in a string
 254  * @s: The string to be searched
 255  * @c: The character to search for
 256  */
 257 char * strchr(const char * s, int c)
 258 {
 259         for(; *s != (char) c; ++s)
 260                 if (*s == '\0')
 261                         return NULL;
 262         return (char *) s;
 263 }
 264 EXPORT_SYMBOL(strchr);
 265 #endif
 266
 267 #ifndef __HAVE_ARCH_STRRCHR
 268 /**
 269  * strrchr - Find the last occurrence of a character in a string
 270  * @s: The string to be searched
 271  * @c: The character to search for
 272  */
 273 char * strrchr(const char * s, int c)
 274 {
 275        const char *p = s + strlen(s);
 276        do {
 277            if (*p == (char)c)
 278                return (char *)p;
 279        } while (--p >= s);
 280        return NULL;
 281 }
 282 EXPORT_SYMBOL(strrchr);
 283 #endif
 284
 285 #ifndef __HAVE_ARCH_STRNCHR
 286 /**
 287  * strnchr - Find a character in a length limited string
 288  * @s: The string to be searched
 289  * @count: The number of characters to be searched
 290  * @c: The character to search for
 291  */
 292 char *strnchr(const char *s, size_t count, int c)
 293 {
 294         for (; count-- && *s != '\0'; ++s)
 295                 if (*s == (char) c)
 296                         return (char *) s;
 297         return NULL;
 298 }
 299 EXPORT_SYMBOL(strnchr);
 300 #endif
 301
 302 #ifndef __HAVE_ARCH_STRLEN
 303 /**
 304  * strlen - Find the length of a string
 305  * @s: The string to be sized
 306  */
 307 size_t strlen(const char * s)
 308 {
 309         const char *sc;
 310
 311         for (sc = s; *sc != '\0'; ++sc)
 312                 /* nothing */;
 313         return sc - s;
 314 }
 315 EXPORT_SYMBOL(strlen);
 316 #endif
 317
 318 #ifndef __HAVE_ARCH_STRNLEN
 319 /**
 320  * strnlen - Find the length of a length-limited string
 321  * @s: The string to be sized
 322  * @count: The maximum number of bytes to search
 323  */
 324 size_t strnlen(const char * s, size_t count)
 325 {
 326         const char *sc;
 327
 328         for (sc = s; count-- && *sc != '\0'; ++sc)
 329                 /* nothing */;
 330         return sc - s;
 331 }
 332 EXPORT_SYMBOL(strnlen);
 333 #endif
 334
 335 #ifndef __HAVE_ARCH_STRSPN
 336 /**
 337  * strspn - Calculate the length of the initial substring of @s which only
 338  *      contain letters in @accept
 339  * @s: The string to be searched
 340  * @accept: The string to search for
 341  */
 342 size_t strspn(const char *s, const char *accept)
 343 {
 344         const char *p;
 345         const char *a;
 346         size_t count = 0;
 347
 348         for (p = s; *p != '\0'; ++p) {
 349                 for (a = accept; *a != '\0'; ++a) {
 350                         if (*p == *a)
 351                                 break;
 352                 }
 353                 if (*a == '\0')
 354                         return count;
 355                 ++count;
 356         }
 357
 358         return count;
 359 }
 360
 361 EXPORT_SYMBOL(strspn);
 362 #endif
 363
 364 /**
 365  * strcspn - Calculate the length of the initial substring of @s which does
 366  *      not contain letters in @reject
 367  * @s: The string to be searched
 368  * @reject: The string to avoid
 369  */
 370 size_t strcspn(const char *s, const char *reject)
 371 {
 372         const char *p;
 373         const char *r;
 374         size_t count = 0;
 375
 376         for (p = s; *p != '\0'; ++p) {
 377                 for (r = reject; *r != '\0'; ++r) {
 378                         if (*p == *r)
 379                                 return count;
 380                 }
 381                 ++count;
 382         }
 383
 384         return count;
 385 }
 386 EXPORT_SYMBOL(strcspn);
 387
 388 #ifndef __HAVE_ARCH_STRPBRK
 389 /**
 390  * strpbrk - Find the first occurrence of a set of characters
 391  * @cs: The string to be searched
 392  * @ct: The characters to search for
 393  */
 394 char * strpbrk(const char * cs,const char * ct)
 395 {
 396         const char *sc1,*sc2;
 397
 398         for( sc1 = cs; *sc1 != '\0'; ++sc1) {
 399                 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
 400                         if (*sc1 == *sc2)
 401                                 return (char *) sc1;
 402                 }
 403         }
 404         return NULL;
 405 }
 406 EXPORT_SYMBOL(strpbrk);
 407 #endif
 408
 409 #ifndef __HAVE_ARCH_STRSEP
 410 /**
 411  * strsep - Split a string into tokens
 412  * @s: The string to be searched
 413  * @ct: The characters to search for
 414  *
 415  * strsep() updates @s to point after the token, ready for the next call.
 416  *
 417  * It returns empty tokens, too, behaving exactly like the libc function
 418  * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
 419  * Same semantics, slimmer shape. ;)
 420  */
 421 char * strsep(char **s, const char *ct)
 422 {
 423         char *sbegin = *s, *end;
 424
 425         if (sbegin == NULL)
 426                 return NULL;
 427
 428         end = strpbrk(sbegin, ct);
 429         if (end)
 430                 *end++ = '\0';
 431         *s = end;
 432
 433         return sbegin;
 434 }
 435
 436 EXPORT_SYMBOL(strsep);
 437 #endif
 438
 439 #ifndef __HAVE_ARCH_MEMSET
 440 /**
 441  * memset - Fill a region of memory with the given value
 442  * @s: Pointer to the start of the area.
 443  * @c: The byte to fill the area with
 444  * @count: The size of the area.
 445  *
 446  * Do not use memset() to access IO space, use memset_io() instead.
 447  */
 448 void * memset(void * s,int c,size_t count)
 449 {
 450         char *xs = (char *) s;
 451
 452         while (count--)
 453                 *xs++ = c;
 454
 455         return s;
 456 }
 457 EXPORT_SYMBOL(memset);
 458 #endif
 459
 460 #ifndef __HAVE_ARCH_MEMCPY
 461 /**
 462  * memcpy - Copy one area of memory to another
 463  * @dest: Where to copy to
 464  * @src: Where to copy from
 465  * @count: The size of the area.
 466  *
 467  * You should not use this function to access IO space, use memcpy_toio()
 468  * or memcpy_fromio() instead.
 469  */
 470 void * memcpy(void * dest,const void *src,size_t count)
 471 {
 472         char *tmp = (char *) dest, *s = (char *) src;
 473
 474         while (count--)
 475                 *tmp++ = *s++;
 476
 477         return dest;
 478 }
 479 EXPORT_SYMBOL(memcpy);
 480 #endif
 481
 482 #ifndef __HAVE_ARCH_MEMMOVE
 483 /**
 484  * memmove - Copy one area of memory to another
 485  * @dest: Where to copy to
 486  * @src: Where to copy from
 487  * @count: The size of the area.
 488  *
 489  * Unlike memcpy(), memmove() copes with overlapping areas.
 490  */
 491 void * memmove(void * dest,const void *src,size_t count)
 492 {
 493         char *tmp, *s;
 494
 495         if (dest <= src) {
 496                 tmp = (char *) dest;
 497                 s = (char *) src;
 498                 while (count--)
 499                         *tmp++ = *s++;
 500                 }
 501         else {
 502                 tmp = (char *) dest + count;
 503                 s = (char *) src + count;
 504                 while (count--)
 505                         *--tmp = *--s;
 506                 }
 507
 508         return dest;
 509 }
 510 EXPORT_SYMBOL(memmove);
 511 #endif
 512
 513 #ifndef __HAVE_ARCH_MEMCMP
 514 /**
 515  * memcmp - Compare two areas of memory
 516  * @cs: One area of memory
 517  * @ct: Another area of memory
 518  * @count: The size of the area.
 519  */
 520 #undef memcmp
 521 int memcmp(const void * cs,const void * ct,size_t count)
 522 {
 523         const unsigned char *su1, *su2;
 524         int res = 0;
 525
 526         for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
 527                 if ((res = *su1 - *su2) != 0)
 528                         break;
 529         return res;
 530 }
 531 EXPORT_SYMBOL(memcmp);
 532 #endif
 533
 534 #ifndef __HAVE_ARCH_MEMSCAN
 535 /**
 536  * memscan - Find a character in an area of memory.
 537  * @addr: The memory area
 538  * @c: The byte to search for
 539  * @size: The size of the area.
 540  *
 541  * returns the address of the first occurrence of @c, or 1 byte past
 542  * the area if @c is not found
 543  */
 544 void * memscan(void * addr, int c, size_t size)
 545 {
 546         unsigned char * p = (unsigned char *) addr;
 547
 548         while (size) {
 549                 if (*p == c)
 550                         return (void *) p;
 551                 p++;
 552                 size--;
 553         }
 554         return (void *) p;
 555 }
 556 EXPORT_SYMBOL(memscan);
 557 #endif
 558
 559 #ifndef __HAVE_ARCH_STRSTR
 560 /**
 561  * strstr - Find the first substring in a %NUL terminated string
 562  * @s1: The string to be searched
 563  * @s2: The string to search for
 564  */
 565 char * strstr(const char * s1,const char * s2)
 566 {
 567         int l1, l2;
 568
 569         l2 = strlen(s2);
 570         if (!l2)
 571                 return (char *) s1;
 572         l1 = strlen(s1);
 573         while (l1 >= l2) {
 574                 l1--;
 575                 if (!memcmp(s1,s2,l2))
 576                         return (char *) s1;
 577                 s1++;
 578         }
 579         return NULL;
 580 }
 581 EXPORT_SYMBOL(strstr);
 582 #endif
 583
 584 #ifndef __HAVE_ARCH_MEMCHR
 585 /**
 586  * memchr - Find a character in an area of memory.
 587  * @s: The memory area
 588  * @c: The byte to search for
 589  * @n: The size of the area.
 590  *
 591  * returns the address of the first occurrence of @c, or %NULL
 592  * if @c is not found
 593  */
 594 void *memchr(const void *s, int c, size_t n)
 595 {
 596         const unsigned char *p = s;
 597         while (n-- != 0) {
 598                 if ((unsigned char)c == *p++) {
 599                         return (void *)(p-1);
 600                 }
 601         }
 602         return NULL;
 603 }
 604 EXPORT_SYMBOL(memchr);
 605 #endif